Interactive automatic external defibrillator providing attachment guidance to operator

ABSTRACT

A method for operating an automatic external defibrillator (AED) prompts an operator about proper operation of the automatic external defibrillator and placement of the electrodes to ensure rapid and proper operation. Depending upon a state of a pad storage compartment, upon activation the AED issues an initial prompt, pauses after the initial prompt and then issues a second prompt. The AED also determines whether the pads have been removed from a liner and if so, issues a pad application prompt. The AED next determines whether both pads have been placed and if so, analyzes an impedance signal and if the impedance signal is erratic, issues a pad correction prompt. The AED also issues the pad correction prompt if the pads are removed from the liner but never go on the patient.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional application Ser.No. 60/420,767 filed Oct. 23, 2002, which is incorporated herein byreference.

The present invention is directed to methods and apparatuses forinteracting with operators of automatic external defibrillators, andmore particularly to a method and apparatus for interacting with anoperator of an automatic defibrillator to ensure proper operation.

Existing Automatic External Defibrillators (AEDs) deliver a series ofvoice prompts when activated, which include prompts to deploy electrodesfrom their container, attach the electrodes to the patient, and plug inthe pads of the connector at a specified location. However, existingAEDs do not sense intermediate steps in this process nor offer specificguidance during pad deployment and attachment. Thus, the mostskill-intensive steps in the operation of the AED must be performed“open-loop” by the operator. These deployment steps are the most proneto operator error.

A persistent problem with prior AEDs was that following initial “applypads” prompts, operators were required to perform a detailed series ofskilled operations in order to attach the AED and its electrode pads tothe patient. The operator has to: assure that emergency medical servicesare called, remove clothing from the patient's chest, find a package ofAED electrodes, open the bag and remove the electrodes, peel eachelectrode from a backing, place each pad in a proper location on thepatient's chest, assure that the electrodes are adhered correctly, andplug in the lead wires from the pads to the AED (in some devices).Existing AEDs could next sense if the pads were connected to appropriateimpedance and proceed to perform ECG analysis. However, errors in theintervening attachment steps often resulted in inconsistent or poor padplacement accuracy, or in a wide variation in the time taken to performall steps due to operator confusion. This situation is exacerbated bythe extreme stress under which an untrained operator is typicallyperforming these tasks. Moreover, most potential operators of an AED arenot normally trained to perform the requisite tasks under these highstress situations.

The present invention is therefore directed to the problem of developinga method and apparatus for facilitating the proper operation of an AED,and in particular facilitating proper deployment of the pads.

The present invention solves these and other problems by providing,inter alia, an Automatic External Defibrillator (AED) that interactswith the operator during the initial phases of a rescue or operation. Inparticular, according to one exemplary embodiment of the AED of thepresent invention, the embodiment senses various progressive states ofpad deployment and attachment, and provides specific operator guidance(e.g., one or more prompts) based upon this sensed information.

According to an exemplary embodiment of a method for operating an AED,various device operating conditions are determined following deviceactivation. Knowledge of the operating conditions of the device allowsspecialized instructions to be delivered during sequential phases ofelectrode pad deployment and placement on the patient by the operator.This results in more accurate pads placement and more consistent timeintervals to complete these steps than previous devices.

FIG. 1 depicts an exemplary embodiment of a method for interacting withan operator of an Automatic External Defibrillator according to oneaspect of the present invention.

It is worthy to note that any reference herein to “one embodiment” or“an embodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. The appearances of thephrase “in one embodiment” in various places in the specification arenot necessarily all referring to the same embodiment.

Referring to FIG. 1, shown therein is a flowchart of an exemplaryembodiment 10 of a method for operating an Automatic ExternalDefibrillator (AED) according to one aspect of the present invention.The AED may be activated by either pressing an ON/OFF button or bypulling a lever that removes a protective cover. Thus, the AED mustfirst determine the activation state of itself. This can be accomplishedby noting the state in which the ON/OFF switch or button lies, ordetermining whether a cover is being removed, in which case a contactcan be opened or closed, which can easily be sensed. Alternatively, theAED can sense a change in the state of the ON/OFF button._([KH1])

If the AED is turned ON by pressing the button (determination made inelement 11), the AED issues an initial prompt (element 12 a), in whichthe operator is prompted to (or similar words to this effect):

-   -   1. “BEGIN BY REMOVING ALL CLOTHING FROM THE PATIENT'S CHEST.”    -   2. “CUT CLOTHING IF NEEDED.”    -   3. “CALL EMERGENCY MEDICAL SERVICES.”_([KH2]) This final        instruction may be included in some embodiments and may be left        out in others.

Alternatively, the final instruction may be in the form of a reminder tosimply be sure emergency services have been called.

After a pause timed to permit clothing removal (element 12 b), the AEDissues a second prompt (element 12 c), in which the operator isinstructed (or words similar to these):

-   -   1. “WHEN A PATIENT'S CHEST IS BARE, REMOVE PROTECTIVE COVER AND        TAKE OUT WHITE ADHESIVE PADS.”

This prompt is repeated at predetermined intervals (e.g., every 5seconds) until the AED senses that the protective cover has been removedand that the pads are being handled (determination made in element 12d). If on the other hand, the AED is activated by pulling a handle andremoving a cover (i.e., the button is not used to activate the AED), theAED will repeat the initial prompt (element 13 a), pause (element 13 b),and then issue the second prompt (element 13 c). Then the AED willdetermine if the pads are being handled (element 13 d). If not, the AEDwill repeat elements 13 a-c for a predetermined number of times (e.g.,x=3) and then move on to the next step in the pads deployment procedure,i.e., element 14. In this case, it is assumed that the operator hasremoved the pads from their container but the AED's method for detectingthis event was not able to do so successfully.

Upon detecting pad handling, or after a pre-determined amount of timehas elapsed, the AED then issues a picture prompt (element 14), in whichthe operator is instructed (or with similar words to these):

1. “LOOK CAREFULLY AT THE PICTURES ON THE WHITE ADHESIVE PADS. PEEL ONEPAD FROM THE YELLOW PLASTIC LINER.”

This prompt 14 repeats until the AED senses that a pad has been removedfrom the liner (element 15). While on the liner, the pads are inelectrical contact with one-another and the AED impedance detectioncircuitry senses this state. An alternative is to sense each pad'scontact state individually using two wires to each pad and acontact-completion detector. This prompt 14 is specifically designed tostop an operator and bring attention to the purpose of the icons thatare printed on the pads. Lacking this interruption, naïve users tend tointuitively understand that the pads are to be adhered to the patient,but do not pick up on the fact that the pictures on the pads havesignificance. Thus, operators tend to locate the pads in random fashion,favoring the ineffective side-by-side positioning seen on televisionshows.

Once a pad has been removed from the liner by the operator, the AEDissues a pad application prompt (element 16 a), in which the operator isinstructed (or with words to this effect):

1. “PLACE PAD EXACTLY AS SHOWN IN THE PICTURE.”

2. “PRESS FIRMLY TO PATIENT'S BARE SKIN.”

3. “WHEN THE FIRST PAD IS IN PLACE, LOOK CAREFULLY AT THE PICTURE ON THESECOND PAD.”

4. “PEEL THE SECOND PAD FROM THE YELLOW PLASTIC LINER.”

5. “PLACE PAD EXACTLY AS SHOWN IN THE PICTURE.”

6. “PRESS FIRMLY TO PATIENT'S BARE SKIN.”

Again the prompt sequence repeats as needed until the AED senses thatboth pads are placed (element 17). Rapid pad attachment by an operatorcauses intermediate steps to be skipped or abbreviated. When both padsare in place, the AED proceeds to analyze the patient's ECG signal(element 18). Here again, by use of specific instructions to locate thepads as shown in the pictures, operators are provided informationcrucial to successful placement.

If the pad contact is erratic (determination made in element 19) orotherwise unacceptable for ECG analysis, the AED issues a pad correctionprompt (element 20), in which the operator is instructed (or with wordssimilar to these):

1. “PRESS PADS FIRMLY TO PATIENT'S BARE SKIN.”

2. “MAKE SURE THAT THE YELLOW PLASTIC LINER IS COMPLETELY REMOVED FROMBOTH PADS.”

3. “PLACE PAD EXACTLY AS SHOWN IN THE PICTURE.”

4. “PADS MUST NOT BE TOUCHING CLOTHING OR EACH OTHER.”

Testing has shown that these steps markedly improve operator success.

The AED also issues the pad correction prompt if the pads are removedfrom the liner but never go on the patient (element 16 b), as this wouldsignal that either one of the two pads are broken or that the operatorhas done something like forgotten to remove the plastic liner or hasplaced one or both pads on clothing._([KH3])

In summary, the AED of the present invention provides several featuresto ensure rapid and correct operation. For example, the AED includes aprovision for sensing and prompting steps between device turn-on and padattachment, thus breaking down a complex skill requirement into severalsimple ones. Furthermore, two different prompt sequences are employeddepending upon how the AED is activated (e.g., by button or handle).Additionally, the AED includes a provision for an operator prompt tocall emergency medical services, which can be forgotten in the panic ofthe moment in which an AED is likely to be employed. Moreover, the AEDincludes an operator prompt to remove cover and take out pads. The AEDalso includes the capability to sense when pads are being handled, evenwhen the pads are still on their liner, and to issue associated promptsfor the next step. This is a key prompt for placement accuracy, withoutit AEDs have markedly poor performance. Still further, the AED includesthe capability to sense when one pad has been removed from its liner,and to issue appropriate prompts for what to do next. Yet, the AED alsoincludes a prompt to place the pads as shown in pictures on the pads.This picture prompt one is very effective and valuable, as otherwise thepads are often placed in an incorrect or ineffective position. The AEDalso includes prompts providing visual differentiation to elements thatmust be handled by the operator, such as: “White adhesive pads,” “yellowplastic liner,” and pictures noted on pads. In addition, the AEDincludes error correction prompts if pad contact is erratic that isspecific to correcting certain typical problems, such as pads touchingeach other, failure to remove or release the liner, or pads being placedon clothing. Other features of the exemplary AED are evident from thedescription above.

Although various embodiments are specifically illustrated and describedherein, it will be appreciated that modifications and variations of theinvention are covered by the above teachings and are within the purviewof the appended claims without departing from the spirit and intendedscope of the invention. For example, specific operator instructions areprovided, however, similar instructions conveying similar informationmay also be used. Furthermore, this example should not be interpreted tolimit the modifications and variations of the invention covered by theclaims, but is merely illustrative of one possible variation.

1. A method for guiding an operator of an automatic externaldefibrillator in pad placement on a subject comprising: prompting anoperator to conduct a pad placement action; sensing whether the pads arein proper contact with the subject and, if they are not; followingsensing, issuing a pad correction prompt to remove a pad liner.
 2. Amethod for guiding an operator of an automatic external defibrillator inpad placement on a subject comprising: prompting an operator to conducta pad placement action; sensing whether the pads are in proper contactwith the subject and, if they are not; following sensing, issuing a padcorrection prompt that the pads must not be touching each other.
 3. Themethod according to claim 1, further comprising repeating a prompt untilthe defibrillator senses that the operator has conducted the promptedaction.
 4. The method according to claim 2, further comprising repeatinga prompt until the defibrillator senses that the operator has conductedthe prompted action.